Publication Date:
2020-07-31
Description:
Populations of the sepioid Idiosepius pygmaeus were located in mangrove and estuarine localities in the Townsville region of North Queensland Australia in 1986. This species was small, easy to observe and collect in the field and sexually dimorphic, with females being much larger than males. Statolith microstructures of I. pygmaeus proved to be a useful ageing tool which can be used to interpret life history phenomena in this species. Increments were calibrated by marking statoliths in situ with tetracycline and counting the rings laid down subsequent to marking. This validated the daily periodicity of the observed rings. Statolith discontinuities (checks) were occasionally seen within the microstructures of some specimens. These discontinuities appear to parallel similar structures found in fish otoliths. Based on statolith analysis, I. pygmaeus matured at an age of 11/2-2 months. Females were larger and grew faster than their male counterparts. Females of similar age were found to vary considerably in size. The estimates of growth rates and longevity for I. pygmaeus suggested multiple generations within one year.
Type:
Article
,
PeerReviewed
Format:
text
